Health Science Campus

Collier Building, RM 4405

lead and your health

Tremendous progress has been made in the United States to reduce lead exposure and
to lower blood lead levels.1 Much of this success is due to research supported by
the National Institute of Environmental Health Sciences (NIEHS) and others who have
helped to identify and reduce the health effects of lead exposure in children and
adults.

What is lead?

Lead is a naturally occurring metal found deep in the ground. It occurs in small amounts
in ore, along with other elements such as silver, zinc, or copper. Even though it
is found in small amounts, there is an abundant supply of lead throughout the earth.
Because it is widespread, and easy to extract and work with, lead was used for hundreds
of years in a wide variety of products found in and around homes, including paint
and gasoline. Where is lead found now? Lead can still be found in lead-based paint used in older homes, contaminated soil,
household dust, drinking water pumped through leaded pipes, lead crystal, lead-glazed
pottery, airplane fuel, some toys, and some inexpensive metal jewelry. Until 1978,
lead paint was commonly used on the interior and exterior of homes. Deteriorated lead
paint in older housing remains the most common source of lead exposure for children
in the United States.

How does lead get into the body?

Lead can get into your body in two ways - through breathing it in or by eating it.
For example, lead can enter the body through eating or inhaling paint dust or chips.
The soil around your home can pick up lead from sources such as exterior paint. Lead
can also enter your drinking water through your plumbing.

Who is most vulnerable to the effects of lead? Both children and adults are vulnerable
to the effects of lead. Young children under the age of 5 are particularly vulnerable,
because their body, brain, and metabolism are still develloping. Two-year-olds tend
to have the highest blood level concentration, because they put many things into their
mouth, including toys or other products that may contain lead.

How do you measure lead exposure?

Blood tests are typically used to measure the concentration or amount of lead in your
blood, and are used to detect lead in both children and adults. Although long-standing
national surveys, such as the National Health and Nutrition Examination Survey, show
that blood lead levels have decreased over the last 30 years for all age groups, black,
non-Hispanic children have higher levels of lead detectable in their blood.2 A person's
blood lead level reflects both the current environmental exposure and previous lead
exposures stored in body tissues, primarily in bone.

Measuring bone lead requires specialized testing equipment, whereas blood lead testing
is the most readily available indicator for lead exposure.

What are the effects of lead in children?

Exposure to lead can have a wide range of effects on a child's development and behavior.
Blood lead levels less than 10 micrograms per deciliter (µg/dL) are associated with
increased behavioral effects, delayed puberty, and decreases in hearing, cognitive
performance, and postnatal growth or height. Some of these health effects are found even at low blood lead levels less than 5 µg/dl,
including lower IQ scores, decreased academic achievement, and increases in both behavioral
problems and attention ­related behaviors. There is a wide range of lead­associated
behavioral effects in the area of attention. Attention deficit hyperactivity disorder
(ADHD) is one example on the more severe end of the spectrum.

What are the health effects of lead in adults?

Lead exposure has been linked to a number of health effects in adults. As a general
rule, the more lead you have in your body, the more likely it is you'll have health
problems. High blood lead levels greater than 15 µg/dl are associated with cardiovascular
effects, nerve disorders, decreased kidney function, and fertility problems, including
delayed conception and adverse effects on sperm and semen, such as lower sperm counts
and motility.

Blood lead levels belowlO µg/dl are associated with decreased kidney function and
increases in blood pressure, hypertension, and incidence of essential tremor, a degenerative
disorder of the central nervous system whose most recognizable feature is a tremor of the arms or hands during voluntary movements, such as eating and writing.
There is also evidence showing that adults who have low levels of exposure to lead
less than 5 µg/dl may have decreased kidney function.

Pregnant women need to be particularly careful around lead. Maternal blood lead levels
less than 5 µg/dl are associated with reduced fetal growth. Because the effects of
lead are different for everyone, more research needs to be done to fully understand
the health effects.

A 2004 study, supported by NIIEHS, also showed that lifetime lead exposure may increase
the risk of developing cataracts,3 a clouding of the eye lens resulting in partial
loss of vision, which can be common in older people. Most adults with elevated blood
lead levels are exposed to lead at work. Those in occupations related to mining, ironwork
or welding, construction, renovation and remodeling activities, smelters, firing ranges,
the manufacture and disposal of car batteries, automobile radiator repair, metal shop
work, and the manufacture of pottery or stained glass are particularly at risk for
lead exposure.

How much lead is harmful?

No amount of lead is safe. Eliminating all lead exposure in our environment is our
best course of action. New findings from NIEHS-supported grantees, as well as the National Toxicology Program
(NTP), provide support for many adverse health effects in both children and adults
at blood lead levels below 1 O µg/dL, and, for some, below 5 µg/dl.

These findings add to the body of evidence that led the Centers for Disease Control
and Prevention (CDC), in 2012, to update its reference value to identify children who have been exposed
to lead and who require case management. The new level is based on the population
of children aged 1-5 years, in the U.S., who are in the top 2.5 percent of children
when tested for lead in their blood.4 Currently, this means that public health actions
be initiated for children with blood lead levels above 5 µg/dl. Prior to this, children
were identified as having a blood lead level of concern if the test result was 10
µg/dL or more.5 As part of a shift in focus to primary prevention of lead exposure, the
CDC has dropped the level of concern terminology, since no safe blood lead level in
children has been identified. The new, lower value gives parents, doctors, and public
health officials an opportunity to prevent and reduce lead exposure very early on.

Are there treatments to remove lead from the body? Yes, medications exist that can
remove some lead from the body. However, no medical treatment is recommended for children
with blood lead levels lower than 45 µg/dl. Medications, such as succimer, have been
shown to significantly reduce lead in children with very high blood lead levels.6
Although succimer lowered blood lead about 25% in the short term, it did not improve
IQ or other test scores. This reinforces the need for prevention. Treatment after the fact does not undo the
damage caused by lead. Children must be protected from being exposed at all.